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The canonical Wnt pathway regulates the metastasis-promoting mucin MUC4 in pancreatic ductal adenocarcinoma. Mol Oncol 2016 Feb;10(2):224-39

Date

11/04/2015

Pubmed ID

26526617

Pubmed Central ID

PMC4740200

DOI

10.1016/j.molonc.2015.10.005

Scopus ID

2-s2.0-84958924067   24 Citations

Abstract

Aberrant Wnt signaling frequently occurs in pancreatic cancer (PC) and contributes to disease progression/metastases. Likewise, the transmembrane-mucin MUC4 is expressed de novo in early pancreatic intraepithelial neoplasia (PanINs) and incrementally increases with PC progression, contributing to metastasis. To determine the mechanism of MUC4 upregulation in PC, we examined factors deregulated in early PC progression, such as Wnt/β-catenin signaling. MUC4 promoter analysis revealed the presence of three putative TCF/LEF-binding sites, leading us to hypothesize that MUC4 can be regulated by β-catenin. Immunohistochemical (IHC) analysis of rapid autopsy PC tissues showed a correlation between MUC4 and cytosolic/nuclear β-catenin expression. Knock down (KD) of β-catenin in CD18/HPAF and T3M4 cell lines resulted in decreased MUC4 transcript and protein. Three MUC4 promoter luciferase constructs, p3778, p3000, and p2700, were generated. The construct p3778, encompassing the entire MUC4 promoter, elicited increased luciferase activity in the presence of stabilized β-catenin. Mutation of the TCF/LEF site closest to the transcription start site (i.e., -2629/-2612) and furthest from the start site (i.e., -3425/-3408) reduced MUC4 promoter luciferase activity. Transfection with dominant negative TCF4 decreased MUC4 transcript and protein levels. Chromatin immunoprecipitation confirmed enrichment of β-catenin on -2629/-2612 and -3425/-3408 of the MUC4 promoter in CD18/HPAF. Functionally, CD18/HPAF and T3M4 β-catenin KD cells showed decreased migration and decreased Vimentin, N-cadherin, and pERK1/2 expression. Tumorigenicity studies in athymic nude mice showed CD18/HPAF β-catenin KD cells significantly reduced primary tumor sizes and metastases compared to scrambled control cells. We show for the first time that β-catenin directly governs MUC4 in PC.

Author List

Pai P, Rachagani S, Lakshmanan I, Macha MA, Sheinin Y, Smith LM, Ponnusamy MP, Batra SK

Author

Yuri M. Sheinin MD, PhD Assistant Professor in the Pathology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Carcinogenicity Tests
Carcinoma, Pancreatic Ductal
Cell Line, Tumor
Female
Gene Knockdown Techniques
Humans
Mice
Mice, Nude
Mucin-4
Neoplasm Metastasis
Pancreatic Neoplasms
Promoter Regions, Genetic
Transcription Factor 7-Like 2 Protein
Up-Regulation
Wnt Signaling Pathway
beta Catenin